Add turn tracking and enforce turn order

Introduce CurrentTurn to Game (default 1) and expose it via GameInformationDto. Update GameManager to include CurrentTurn in the GameInformation payload, validate that a player can only Drop when it is their turn, and toggle CurrentTurn between 1 and 2 after a successful move. Also use a safe fallback (0) when game is null.

API/Models/Game/Game.cs

@@ -14,6 +14,7 @@ public class Game(Coordinates gFs, SixDigitInt gameCode)
     public string Id { get; init; } = Guid.NewGuid().ToString();
     public SixDigitInt GameCode { get; } = gameCode;
     public List<Player> Players { get; set; } = new();
+    public int CurrentTurn { get; set; } = 1;
     public GameState State { get; private set; } = GameState.Lobby;
     public GameField Field { get; } = new(gFs);
     

API/Models/Game/GameInformationDto.cs

@@ -6,5 +6,6 @@
         public List<Player> Players { get; set; }
         public GameState? State { get; set; }
         public int[,] CurrentField { get; set; }
+        public int CurrentTurn { get; set; }
     }
 }

API/Services/GameManager/GameManager.cs

@@ -43,7 +43,8 @@ public class GameManager(IGameRepository gameRepository, IHubContext<GameHubSock
         {
             Players = game?.Players,
             CurrentField = game?.Field.CurrentField,
-            State = game?.State
+            State = game?.State,
+            CurrentTurn = game?.CurrentTurn ?? 0
         };
 
         await hubContext.Clients.Client(playerConnectionId).SendAsync("GameInformation", gameInfoDto);
@@ -57,6 +58,9 @@ public class GameManager(IGameRepository gameRepository, IHubContext<GameHubSock
         if (player == null)
             return;
 
+        if(game.CurrentTurn != player.PlayerTag) 
+            return;
+
         var result = game.Field.Drop(column, player.PlayerTag);
 
         if (result != DropResult.Placed)
@@ -92,6 +96,8 @@ public class GameManager(IGameRepository gameRepository, IHubContext<GameHubSock
 
             ScheduleGameDeletion(game.Id, TimeSpan.FromSeconds(5));
         }
+
+        game.CurrentTurn = game.CurrentTurn == 1 ? 2 : 1;
     }
 
     public Task DisconnectedPlayer(string playerConnectionId)